1. Field of the Invention
The present invention belongs to a medical and biology field such as cell biology, pathology and biochemistry, and in particular relates to a method for reacting a reagent to a living sample and a method for detecting a reaction product.
2. Description of the Related Art
Due to the recent development of genome analysis, the importance of analysis of protein which is a gene product present in a living body has rapidly attracted considerable attention. Among others, the importance of protein analysis in tissue sections is being recognized. For example, many attempts have been made to elucidate the proteins in cancer tissue sections which are involved in recurrence and metastasis. Microscopic observation has often been used as a method for analyzing surface proteins in living samples of cells and tissues. In this case, methods have been used in which a target substance is labeled through a specific antibody, and the color, light emission, fluorescence or the like of the label is detected to identify the protein target. Recently, for example a method is described in Japanese Patent Application Laid-Open No. 2001-249125 in which a sample section is directly irradiated with a laser to obtain a mass spectrum. Further, for means of directly treating the surface of a living sample, analysis of the living sample has been performed by directly applying a reagent to the living sample whose amount and position has been controlled using an ink-jet method as described in Japanese Patent Application Laid-Open No. 2004-347594. Still further, for visualizing two dimensional distribution of protein and the like in fine details at cellular level in a living sample, a method and a device to obtain information based on the TOF-SIMS method (the time-of-flight secondary ion mass spectrometry) are disclosed in the International Publication No. WO2005/003715. In this method, after directly applying ionizing agents and/or digestive enzymes to the living sample using an ink-jet method or the like, while keeping the positional information, the TOF-SIMS method that has a high space resolving power in sub-micrometer level is performed. By this method, the information related to the kind of proteins in the reaction product (including the information as to the limited digested peptides by the digestive enzyme) can be visualized.
Information as to the distribution of a reaction product in a living sample can be obtained by the methods described in the Japanese Patent Application Laid-Open No. 2004-347594 and International Publication No. WO2005/003715. However, to obtain the two dimensional distribution information in a finer level such as the distribution within a cell size diameter (10 μm), an improvement for the method of discharging droplets in the ink-jet is required. This is because, although the volume of the droplet of the ink-jet for supplying reagents is normally as small as 1 pl-100 pl, the dot size diameter, when dropped on the living sample, becomes as large as 10 μm to 1000 μm. For this reason, when the objective is to obtain the information within a normal single cell size range, problems arise such as widening of the distribution due to the diffusion and elution of the reagents, or lowering of the reaction conditions due to the evaporation of the reagents. Therefore, when the information of the two dimensional distribution within the single cell size range is to be obtained, the reagent must be applied individually in a finer region of the living sample, and held there for a certain period of time until the reaction is completed while preventing the diffusion and evaporation of the droplet as much as possible. If the two dimensional distribution of the sample and the reaction products can be analyzed more accurately for proteins in cells in a specific lesion such as cancer cells or proteins in the neighboring cells to the cancer cells in a living sample analysis, it would contribute to the development of a diagnostic device and drug discovery device.